There are many instances where target compounds in a biological sample need to be detected and analyzed. For example, in diagnostic laboratories, it is necessary to detect the presence of particular compounds, such as steroids, in biological samples such as a blood or urine sample. In another example, the presence and/or concentration of particular compounds, again such as steroids, in particular biological samples, such as blood samples, can be a diagnostic indicator of possible disease states in a patient. Further, the current research into the use of disease markers to diagnose possible disease states in patients is identifying many specific molecules whose presence in particular biological samples may indicate the presence of a particular disease states in a patient. Therefore, it is necessary to be able to detect and analyze these target compounds in biological samples as directly as possible.
In connection with blood samples, blood serum, which often contains the target compounds and often is used as the biological blood sample for diagnostic and testing purposes, presents challenges for the physical detection of target compounds. This is because the target compounds are present in the sample at substantially lower concentrations as compared to other molecules. Proteins/peptides in particular can cause interference problems with many current separation methods. With current separation and analysis methods, some or all of these proteins are removed from the serum prior to determining whether or not the target compounds are present. Thus, current analysis methods usually require two or more separation methods to be able to identify a target compound present in the complex mixture of compounds present in serum and other biological samples. The method describes a way to measure molecules directly from whole serum by weak-affinity liquid chromatography-mass spectrometry.